The present invention relates to a compact fluorescent lamp assembly, and more particularly, to an LED integrated compact fluorescent lamp assembly.
Prior art solutions to low color rendering of compact fluorescent lamps (CFL) have concentrated on optical properties, phosphors, CRI, etc. Although full spectrum fluorescent lamps exist, these lamps have low lumens per watt (LPW), poor color and lumen maintenance, or low color rendering of the color red. Therefore, the red containing colors seem significantly different when illuminated by a conventional CFL compared to an incandescent lamp or natural sunlight. For example, certain colors lack the vivid, very apparent red color with conventional CFL light sources. There are high color rendering CFLs in the market that use phosphors to address the desired color rendering.
Unfortunately, the phosphor solution for enhancing color quality is inadequate because the discharge deteriorates the phosphor and the lumen maintenance and color stability of these lamps do not meet customer requirements.
Adding a small portion (approximately 5-10% of the white light produced by the CFL) of red light produced by a light-emitting diode (“LED”) based light source to the white light provided by the CFL is another solution to enhance the red color rendering.
On the other hand, adding the red color via an LED encounters issues because currently available high efficiency red LEDs are temperature sensitive. The lumen output of the LED decreases significantly upon increasing ambient temperature. For example, warming to 80 C, the efficiency and lumen output of the LED decreases to approximately half of the values measured at 25 C. Unfortunately, the working temperature of a low-pressure fluorescent discharge tube or CFL is approximately 80-110 C, and the surrounding components (e.g., outer bulb and ballast) are heated to approximately 60-70 C by heat conduction and convection. Thus, the LED has to be thermally insulated from the CFL, and the heat produced by the LED (approximately 1-3 W) has to be dissipated in order maximize the efficiency and lumen output of the LED.
As a result, a need exists for a lamp assembly that provides light mixing and thermal management solutions of an LED light source that is combined with a CFL light source in order to improve light quality and color rendering with a desired useful life.